Search for first-generation scalar leptoquarks in pp̄ collisions at √s = 1.96 TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 71:7 (2005) 1-7
Abstract:
We report on a search for pair production of first-generation scalar leptoquarks (LQ) in pp̄ collisions at √s = 1.96 TeV using an integrated luminosity of 252 pb-1 collected at the Fermilab Tevatron collider by the D0 detector. We observe no evidence for LQ production in the topologies arising from LQLQ → eqeq and LQLQ → eqvq, and derive 95% C.L. lower limits on the LQ mass as a function of β, where β is the branching fraction for LQ → eq. The limits are 241 and 218 GeV/c 2 for β = 1 and 0.5, respectively. These results are combined with those obtained by D0 at √s = 1.8 TeV, which increases these LQ mass limits to 256 and 234 GeV/c2. © 2005 The American Physical Society.Measurement of the Lambda0b lifetime in the decay lambda0b--> J/psiLambda0 with the D0 detector.
Phys Rev Lett 94:10 (2005) 102001
Abstract:
We present measurements of the Lambda(0)(b) lifetime in the exclusive decay channel Lambda(0)(b)--> J/psiLambda(0), with J/psi--> mu(+)mu(-) and Lambda(0)--> ppi(-), the B0 lifetime in the decay B0-->J/psiK(0)(S) with J/psi--> mu(+)mu(-) and K(0)(S)-->pi(+)pi(-), and the ratio of these lifetimes. The analysis is based on approximately 250 pb(-1) of data recorded with the D0 detector in pp collisions at sqrt[s] = 1.96 TeV. The Lambda(0)(b) lifetime is determined to be tau(Lambda(0)(b)) = 1.22(+0.22)(-0.18)(stat) +/- 0.04(syst) ps, the B0 lifetime tau(B0) = 1.40(+0.11)(-0.10)(stat) +/- 0.03(syst) ps, and the ratio tau(Lambda(0)(b))/tau(B0) = 0.87(+0.17)(-0.14)(stat) +/- 0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Lambda(0)(b) lifetime based on a fully reconstructed decay channel.Measurement of the Λ b 0 lifetime in the decay Λ b 0 → J/ψΛ 0 with the D0 detector
Physical Review Letters 94:10 (2005)
Abstract:
We present measurements of the Λ b0 lifetime in the exclusive decay channel Λ b0 → J/ψΛ 0with J/ψ → μ +μ - and Λ 0 → pπ -, the B 0 lifetime in the decay B 0 → J/ψ/K s0 with J/ ψ → μ + μ - and K s0 → π + π -, and the ratio of these lifetimes. The analysis is based on approximately 250 pb -1 of data recorded with the D0 detector in pp̄ collisions at √s = 1.96 TeV. The Λ b0 lifetime is determined to be τ(Λ b0) = 1.22 -0.18+0.22(stat) ± 0.04(syst) ps, the B 0 lifetime τ(B 0) = 1.40 -0.100.11(stat) ± 0.03(syst) ps, and the ratio τ(Λ b0)/ τ(B 0) = 0.87- 0.140.17(stat) ± 0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Λ b0 lifetime based on a fully reconstructed decay channel. © 2005 The American Physical Society.Search for Wbb̄ and W H production in pp̄ collisions at √s = 1.96 TeV
Physical Review Letters 94:9 (2005)
Abstract:
We present a search for Wbb̄ production in pp̄ collisions at √s = 1.96 TeV in events containing one electron, an imbalance in transverse momentum, and two b-tagged jets. Using 174 pb-1 of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on Wbb̄ production of 6.6 pb for b quarks with transverse momenta pTb > 20 GeV and bb̄ separation in pseudorapidity-azimuth space δRbb > 0.75. Restricting the search to optimized bb̄ mass intervals provides upper limits on WH production of 9.0-12.2 pb for Higgs-boson masses of 105-135 GeV. © 2005 The American Physical Society.Search for the flavor-changing neutral current decay Bs 0 → μ+ μ- pp̄ Collisions at √s = 1.96 TeV with the DO Detector
Physical Review Letters 94:7 (2005)